The brain is more mechanically connected to the body than previously appreciated, scientists reported today (April 27) in Nature Neuroscience. Through a study using mice and simulations, the team found a potential biological mechanism underlying why exercise is thought to benefit brain health: abdominal contractions compress blood vessels connected to the spinal cord and the brain, enabling the organ to gently move within the skull. This swaying facilitates the surrounding cerebrospinal fluid to flow over the brain, potentially washing away neural waste that could cause problems for brain function.
According to Patrick Drew, professor of engineering science and mechanics, of neurosurgery, of biology and of biomedical engineering at Penn State, the work builds on previous studies detailing how sleep and neuron loss can influence how and when cerebrospinal fluid flushes through the brain.
"Our research explains how just moving around might serve as an important physiological mechanism promoting brain health," said Drew, corresponding author on the paper. "In this study, we found that when the abdominal muscles contract, they push blood from the abdomen into the spinal cord, just like in a hydraulic system, applying pressure to the brain and making it move. Simulations show that this gentle brain movement will drive fluid flow in and around the brain. It is thought the movement of fluid in the brain is important for removing waste and preventing neurodegenerative disorders. Our research shows that a little bit of motion is good, and it could be another reason why exercise is good for our brain health."
Drew, who also holds the title of associate director of the Huck Institutes of the Life Sciences, explained how in a hydraulic system, a pump creates pressure that drives fluid flow. In this case, the pump is the abdominal contraction - which can be as light as the tensing prior to sitting up or taking a step. The contraction puts pressure on the vertebral venous plexus, a network of veins that connect the abdominal cavity to the spinal cavity, causing the brain to move.
